(1) The Field of the Invention
This invention relates to new polyazo compounds wherein at least two different azo functions are present. Also the invention relates to a method of providing free radicals in sequence wherein a novel polyazo compound, as defined, is used as the source of sequential free radicals. More particularly the invention relates to the preparation of vinyl polymers containing functional azo groups and to block copolymerization using such vinyl-azo polymers.
(2) The Prior Art
Compounds havng more than one azo function have been reported but in all cases the azo functions are identical. Sequential free radical generation would not be observed with the prior art compounds. Such prior art is reported in: U.S. Pat. No. 2,554,141; U.S. Pat. No. 3,244,692; Neugebauer et al, Ann. 706, 107 (1067); Bellamy et al, J. Chem. Soc. C, 1966, 1989; Easer et al, Gummi 11, WT 57-62 (1958).